1. Field of the Invention
The present invention relates to a cooling device for an engine.
2. Description of the Prior Art
Conventional engine cooling devices are classified into two types, i.e., an air cooling type that has only fins on a cylinder head and a cylinder, and a water cooling type that has only water jackets within a cylinder head and a cylinder.
The former air cooling type device suffers from the following disadvantages. (1) The cooling performance is low, and the output power is low and durability is inferior because the cooling device reaches a high temperature. (2) Since the explosion noises and the piston slap noises are leaked from the engine, the resultant noises are loud. (3) Since the thermal distribution over the entire engine is not uniform, thermal deformation is likely to be caused.
On the other hand, the water cooling type device suffers from the following disadvantages. (1) As shown in FIG. 2 a radiator 40 must be provided, for an engine, which leads to an increase in the cost of the engine unit. (2) Since the radiator 40 is arranged separately from an engine body, mountability of the device becomes inferior. (3) A large space is required for arranging the radiator in a vehicle, which makes the compactness of the device inferior. An engine equipped with the water cooling type device is shown, for example, in Japanese Utility Model Unexamined Publication No. 62-35855.